1. Field of the Invention
The present invention relates to a photoprinter, and particularly, to a photoprinter that prints an image on a heat-sensitive recording paper for developing colors in response to heat and fixing colors in response to light.
2. Description of the Background Art
FIG. 5 is a flowchart showing image-printing steps with a conventional photoprinter. Referring to the flowchart, a process for obtaining three image-printed objects of credit-card size will be described.
First, printing of a first image starts (step S1), and yellow printing is performed. Specifically, the color yellow is developed at a low temperature (step S2). Next, a yellow color-developing layer is fixed with ultraviolet light of 419 nm (step S3). Thereafter, magenta printing is performed. Specifically, the color magenta is developed at an intermediate temperature (step S4). Next, a magenta color-developing layer is fixed with ultraviolet light of 365 nm (step S5). Thereafter, cyan printing is performed. Specifically, the color cyan is developed at a high temperature (step S6). Thus, printing process of the first image ends, and the recording paper is cut and one image-printed object is obtained (step S7).
Next, printing of a second image starts (step S8), and yellow printing is performed. Specifically, the color yellow is developed at a low temperature (step S9). Next, a yellow color-developing layer is fixed with ultraviolet light of 419 nm (step S10). Thereafter, magenta printing is performed. Specifically, the color magenta is developed at an intermediate temperature (step S11). Next, a magenta color-developing layer is fixed with ultraviolet light of 365 nm (step S12). Thereafter, cyan printing is performed. Specifically, the color cyan is developed at a high temperature (step S13). Thus, printing process of the second image ends, and the recording paper is cut and another image-printed object is obtained (step S14).
Next, printing of a third image starts (step S15), and yellow printing is performed. Specifically, the color yellow is developed at a low temperature (step S16). Next, a yellow color-developing layer is fixed with ultraviolet light of 419 nm (step S17). Thereafter, magenta printing is performed. Specifically, the color magenta is developed at an intermediate temperature (step S18). Next, a magenta color-developing layer is fixed with ultraviolet light of 365 nm (step S19). Thereafter, cyan printing is performed. Specifically, the color cyan is developed at a high temperature (step S20). Thus, printing process of the third image ends, and the recording paper is cut and still another image-printed object is obtained (step S21).
With the process as described above, the three image-printed objects are obtained and the continuous printing of three images ends (step S22).
FIG. 6 shows images printed on a recording paper with a conventional photoprinter. In FIG. 6, a recording paper 50 includes a printing region 51 of a first image, a printing region 52 of a second image, a printing region 53 of a third image, a dummy printing region 54 of the first image, a dummy printing region 55 of the second image, and a dummy printing region 56 of the third image. These dummy printing regions 54, 55 and 56 are required by a preprocess for stabilizing the image quality of printing regions 51, 52 and 53, and they are cut off when the printing is finished. Therefore, after continuously printing three images, three cut-off pieces are left as by-products of the printing.
In FIG. 6, recording paper 50 further includes a printhead raising position 57 for printing the first image, a printing start position 58 of the first image, a printing end position 59 of the first image, a printing start position 60 of the second image, a printing end position 61 of the second image, a printing start position 62 of the third image, and a printing end position 63 of the third image. Printing end position 59 of the first image is also a printhead raising position for printing the second image. Printing end position 61 of the second image is also a printhead raising position for printing the third image. The region between printhead raising position 57 for printing the first image and printing start position 58 of the first image corresponds to dummy printing region 54, while the region between printing end position 59 of the first image and printing start position 60 of the second image corresponds to dummy printing region 55. Similarly, the region between printing end position 61 of the second image and printing start position 62 of the third image corresponds to dummy printing region 56.
For example, when printing a photograph, an operation of preheating the printhead is required when raising the printhead in order to obtain a photograph of better quality. Accordingly, the dummy printing region is provided as a region for the raised printhead to attain a stabilized state. As the dummy printing region becomes unnecessary after the printing is finished, it is cut to be a cut-off piece. Though the printed colors blur to some extent until the raised printhead attains a stabilized state, the blurred portion (the dummy printing region) is cut off and therefore the intended photograph is obtained in an excellent quality.
However, when continuously printing a plurality of image, as a conventional photoprinter requires for each image the steps of developing the color yellow at a low temperature, fixing a yellow color-developing layer with ultraviolet light of 419 nm, developing the color magenta at an intermediate temperature, fixing a magenta color-developing layer with ultraviolet light of 365 nm, developing the color cyan at a high temperature, and cutting the recording paper, there exist a problem that a long printing time is required. Additionally, since cut-off pieces are produced in the number of the image-printed objects, the recording paper is not effectively, but wastefully, used.
It is noted that, while a conventional technique, Japanese Patent Laying-Open No. 2002-67363 describes fast printing,. which is enabled by heating the entire paper at once without repeating heating and cooling processes on a few-dots unit basis so as to avoid delay in printing caused by cooling periods, it is silent about processes for cutting the printing time and for economizing a printing paper when continuously printing a plurality of images. Therefore, it fails to solve the problems described above.